My project is to control a dual motor model boat via bluetooth hand-held device. I am using an Adafruit feather 32u4 bluefruit LE and Adafruit DC Motor + Stepper FeatherWing Add-on. I am using the Apple IOS Adafruit Bluefreuit BLE app as the controller. I have this part of the design nearly done. I plan to use this in a swimming pool.

How can I have the boat automatically avoid the sides of the pool or any other obstruction? Also how can I have the boat steer toward a buoy in the water?

I'm voting to close this question as off-topic because it is about a challenging and open-ended robotics sensing problem which must be solved before the practical details of the limited aspects that an Arduino could help with can be considered.
– Chris StrattonAug 13 '17 at 15:16

You might be able to accomplish something with underwater sonar transducers on the sides of the boat detecting the walls at one frequency, and also differentialy listening for a sonar beacon on the buoy at another, but this is far beyond the scope of the Arduino site - both in understanding the sonar issues, and in the drive/transducer electronics for underwater use. Similarly, an optical solution will require a far more sophisticated computation platform - the actual spinning the motors that that the Arduino could handle is relatively trivial in comparison.
– Chris StrattonAug 13 '17 at 15:20

Chris, I take your point about being open-ended, but I was unaware that open-ended questions were off-limits. Sorry. I was only asking for some ideas some of which you included in your response. I thank you for that.
– Will MaynardAug 13 '17 at 15:25

Open-ended questions don't really fit the Stack Exchange model in general, but the main point is that this isn't ready for the Arduino site yet - you have a robotics problem, then an electronics one, and only possibly at the end an Arduino one. It does occur though that your needs are likely short range enough that you may not need efficient underwater transducers, but merely audio parts that can tolerate being wet and be operated in bistatic mode - neither of which is true of the HC-SR04 type modules familiar to Arduino folks.
– Chris StrattonAug 13 '17 at 15:32

Thanks for all your feedback Chris. This was my first post and I now have more of an understanding of the types of questions that this site is designed for. Future posts will keep that in mind. I love the site... a great resource for people who enjoy arduino projects like myself.
– Will MaynardAug 13 '17 at 15:51